Patent GB-191229721-A (GB)
Title: Improvements in Telephone Systems having Automatic Switching Apparatus connected Over Junction Lines with a Manual Exchange.
Filed: 1912-12-24
Granted: 1913-12-24
Abstract: 29,721. Siemens Bros. & Co., and Pettigrew, T. Dec. 24. Automatic and semiautomatic exchange systems; metering-systems. -In systems in which a subscriber is connected by automatic switches at one office to a trunk line leading to a second office, where the connexion is completed and supervised by an operator, arrangements are provided by which the operator can actuate the subscriber's meter. Two arrangements are shown in Figs. 1-3 and Fig. 4 respectively. In these Figures, the relay contacts are not shown in graphic relationship with the windings, but are identified by their reference letters, the contacts ra<1>, ra<2>, for instance, belonging to the relay Ra. First arrangement, Figs. 1-3. The subscriber T<1>, having been connected by preliminary selectors VWI, VWII to a group selector GW, operates his impulsesender to connect himself to an idle junction line 5, 6, Fig. 3, terminating in a jack at the desired manual exchange ME. An operator answers the call and completes the connexion in the usual way, and when the wanted subscriber has replied she depresses @ metering-key. This energizes a self-locking relay and extinguishes a metering indicator lamp, but the meter itself is not actuated until the connexion is released, which occurs when the subscriber T' hangs up his receiver. First and second preliminary selectors, VWI, VWII, Fig. 1. When the subscriber T' lifts down his receiver, the line relay Ra is energised and closes the circuit of the rotary magnet Da of his preliminary selector VWI. When the terminals of an idle second preliminary selector VWII are reached, a circuit is closed through both windings of the cut-off relay Ta in series with a relay Rb. The relay Ta cuts out the line relay Ra and rotary magnet Da and shortcircuits its own high-resistance winding 1, through the off-normal contact i, to render the appropriated trunk non - selectable to other switches, while the relay Rb starts the second preliminary selector into action by closing the circuit of its rotary magnet Db. When the terminals of an idle group selector GW, Fig. 2, are reached, a circuit is closed through both windings of the cut-off relay Tb in series with a resistance W<1>, Fig. 2, and the winding- C<2> of a relay C. The relay Tb cuts out the relay Rb and rotary magnet dB and the de-energization of the relay Rb renders the appropriated trunk non-selectable to other switches by shortcircuiting the high-resistance winding 1 of the relay Tb, the second windings of the relays Ta, Tb, which are now energised in series in the test-circuit, being of sufficiently low resistance to secure this effect. Group selector GW, Fig. 2. The relays A, Va, C (represented by its windings C<1>, C<2>) are energized as soon as the selector is seized. The line-interruptions caused by the subscriber's impulse-sender intermittently de-energize the relay A, which closes the circuit of the vertical magnet H to lift the selector wipers to the level of terminals allotted to the junction lines leading to the desired manual exchange. As long as the impulses continue, a slow-acting relay Vb is energized, and the circuit of the relay C, opened at the contact K<2> by the first movement of the selector, is maintained over a contact vb<2>, but when the impulses terminate, the relays Vb and C are de-energized, and a circuit is completed for the rotary magnet D. The rotary movement of the wipers is brought to a stop, when the terminals of an idle junction line are reached, by the re-energization of the relay C, over its winding C<1>, in series with a relay P, Fig. 3. The relay C short-circuits its winding C<1>, to make the appropriated trunk non-selectable, but remains energised by current in the winding C<2>, the contact i having been closed at the first rotary step of the selector. In the interval during which the winding C<2> was opencircuited, the relays Ta, Tb, Fig. 1, were kept energized by a parallel connexion through the resistance W<2>. Junction line signalling-arrangements. The relay P, which belongs to a relay set JRS associated with the out-going end of the junction line 5, 6, closes a circuit over the junction wire 5 to a relay LR at the manual exchange ME, whereby the call lamp CL is energized. This lamp is extinguished at the contact 9 when the operator inserts the plug 11 in the jack 7 to answer the call, a circuit being closed at the same time at the contact 10 to illuminate the lamp ZL, which remains alight until the operator, having completed the connexion, and ascertained that the wanted subscriber has replied, presses the metering-key ZK. This key completes a sleeve circuit for the relay M, which locks itself up, extinguishes the lamp ZL, and prepares a circuit for the junction-line metering-relay ZR, which is not energized, however, until the release of the connexion. Release and metering. When the calling subscriber hangs up his receiver, the relay A, Fig. 2, is de-energized, and a circuit is closed through the off-normal contact K<1> for the relay Ab, Fig. 3, which opens the circuit of the relay LR at the distant end of the junction line. The de-energization of the relay LR lights the supervisory lamp SL and closes the circuit of the junction-line metering-relay ZR, which energizes the group-selector metering-relay ZRa over the wire 12, the contact s<2> having been closed in the meantime by the de-energization of the relay S, which follows upon the deenergization of the slow-acting release relay Va. The relay ZRa connects the small resistance W<3> in parallel with the comparatively high resistance W<1>, thereby increasing the current in the test-circuit through the first and second preliminary selectors sufficiently to energize the meter Z, Fig. 1. The energization of the relay S short-circuits the winding C<2> of the relay C, and after a pause due to its windings being short-circuited (this pause being necessary to give time for the above metering-circuits to be closed), the relay C de-energizes and closes the circuit of the release magnet Ma which releases the group selector. This opens the circuit through the relays Ta, Tb, Fig. 1, and the relay Ta closes a circuit through the rotary magnet Da, which is only opened at the contact i when the preliminary selector VWI regains its normal position. The second preliminary selector VWII has no normal position, but remains in the position in which it was last of use, so that it is at once ready for further service upon the de-energization of the relays Ta, Tb. The release of the group selector also leads to the de-energization of the relays P, Ab, Fig. 3, and the relays M, ZR are de-energized when the operator, observing the signal SL, withdraws the plug 11. Second arrangement, Fig. 4. The subscriber T<2> in this arrangement is connected directly by his preliminary selector VW to an idle junction line 25, 26, no numerical switches being einployed. When the operator has once inserted the answering-jack the release of the connexion becomes dependent on its withdrawal, and the subscriber can therefore signal the operator by tapping his switch-hook to flash the supervisory lamp. The depression of the operator's metering key actuates the meter at once, and by pressing the key repeatedly the meter carr be operated as often as desired. When the preliminary selector VW seizes the junction line 25, 26, with which the relay set JRS is associated, the relays A, P are energized, and the relay P closes a circuit over the junction wire 25 to energize the calling relay LR and lamp CL at the exchange ME. When the operator answers the call, the relay LR and lamp CL are de-energized by the energization of a lowresistance sleeve relay N, while a supervisory relay SR in the operator's cord-circuit is energized in series with a relay B over the junction wire 26. The test circuit 23 is now completed over a contact of the relay B in parallel with a contact of the relay A, so that if the calling subscriber depresses his switchhook, the connexion is not released, the only effect being to illuminate the supervisory lamp SL, which results from the de-energization of the relay SR when the relay A cuts out the low-resistance winding 2 of the relay B from the circuit 26. At the end of the conversation the operator depresses the metering-key ZK. which increases the current in the sleeve circuit sufficiently to energize the high-resistance relay M, which closes a circuit over the junction wire 25 for the relay ZR, which cuts the low-resistance winding 2 of the relay P into the test-circuit 23, so as to increase the current sufficiently to energize the meter Z. When the operator withdraws the plug 31 from the jack 17, the relay B is de-energized, and, if the relay A has also been de-energized by the calling subscriber hanging up his receiver, the circuit 23 is opened and the switch VW returns to its normal position.